I've been stuck for two days on nothing
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honey the codewitch wrote:
I can't put myself in the shoes of a person using my code
As far a I'm concerned, you're already ahead of the game by just considering another person using your code. I see far too many implementations where "oh, someone else might use this code besides me" clearly was never considered. Particularly the way API endpoints are coded. Definitely a WTF, as I see endpoints that are unusable except for the very narrow use case of a specific front-end implementation.
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Client-Side Type-Based Publisher/Subscriber, Exploring Synchronous, "Event-ed", and Worker Thread SubscriptionsI always try to design my APIs like I'm going to be forced to use them. :laugh:
Real programmers use butterflies
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There is no polymorphism. Draw targets are those handles you write to.
draw::point(my_draw_target,spoint16(10,15),color_max::red);
Here,
my_draw_targetis what gets drawn to. above draws a point at (10,16), color of red my_draw_target in this case, is say, screen mode 0 but I now want to switch screen modes// switch the driver to a new screen mode:
auto my_draw_target2 = driver.mode<1>();
// now draw to the new screen
draw::line(my_draw_target2,srect16(0,0,9,14),color_max::antique_white);In the above case, once you have
my_draw_target2,my_draw_targetbecomes persona non grata. How that is handled is the question, meaning what happens if i then try to draw again tomy_draw_target? PS: It may appear that my_draw_target and my_draw_target2 are polymorphic but they are not. They do sort of have a shared interface, but they don't. It's complicated. I bind using templates, not virtual base classesReal programmers use butterflies
So how about wrapping it in a kind of de-reference handler for the user to use. The user only creates one Context object, which contains the current draw_target. Changing modes doesn't create a new object for them, but sets the internal draw_target of the Context. The draw::line methods accept the Context instead of the draw_target and access the internal draw_target. There is much I don't understand about what you're doing with the template binding, so this may not be at all feasible. It's also adding an abstraction layer, and I know you're working in resource constrained environments. However, that abstraction layer may be what you need to present a better API to the user.
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So how about wrapping it in a kind of de-reference handler for the user to use. The user only creates one Context object, which contains the current draw_target. Changing modes doesn't create a new object for them, but sets the internal draw_target of the Context. The draw::line methods accept the Context instead of the draw_target and access the internal draw_target. There is much I don't understand about what you're doing with the template binding, so this may not be at all feasible. It's also adding an abstraction layer, and I know you're working in resource constrained environments. However, that abstraction layer may be what you need to present a better API to the user.
That's not possible because there is no common base to use. Different draw targets are entirely distinct types. Furthermore, each draw target is typed by the type of its pixel. So for example, if you have a
bitmap>andbitmap>, the former indicating a bitmap with 16-bit color RGB pixels and the latter indicating 24-bit RGB, each bitmap is a different type. And it must be because the drawing code for a 16-bit pixel is different than that of a 24-bit pixel because the layout in memory of what it's drawing is different. Abitmap<>is an example of a draw target, but each screen you can draw to is a draw target as well. A draw target is anything you can draw on. Ergo, each screen mode is also a draw target, and if it has a different type of pixel than the next, it must be a different type. There can be no common base since 90% of the drawing methods will take a pixel and that has a particular type. So even if i made a base type, that type would have to be a template. This is generic programming and it's powerful, but it's not polymorphic in the traditional way we think about polymorphism. It sounds like you might be a C++ dev but I don't want to assume. If you're not a C++ dev I'm not sure if there's an analogy for this style of coding in any other language. OO principles only loosely apply here though. GP is a different animal.Real programmers use butterflies
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I have something like that already on my targets.
Real programmers use butterflies
All good then, I'd say! :)
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That's not possible because there is no common base to use. Different draw targets are entirely distinct types. Furthermore, each draw target is typed by the type of its pixel. So for example, if you have a
bitmap>andbitmap>, the former indicating a bitmap with 16-bit color RGB pixels and the latter indicating 24-bit RGB, each bitmap is a different type. And it must be because the drawing code for a 16-bit pixel is different than that of a 24-bit pixel because the layout in memory of what it's drawing is different. Abitmap<>is an example of a draw target, but each screen you can draw to is a draw target as well. A draw target is anything you can draw on. Ergo, each screen mode is also a draw target, and if it has a different type of pixel than the next, it must be a different type. There can be no common base since 90% of the drawing methods will take a pixel and that has a particular type. So even if i made a base type, that type would have to be a template. This is generic programming and it's powerful, but it's not polymorphic in the traditional way we think about polymorphism. It sounds like you might be a C++ dev but I don't want to assume. If you're not a C++ dev I'm not sure if there's an analogy for this style of coding in any other language. OO principles only loosely apply here though. GP is a different animal.Real programmers use butterflies
No, I've never developed anything in C++. Plenty of other languages, including plain C, but not C++. I have a vague theoretical understanding of what you're doing and would love to have time to explore it more (sadly, I don't) Logically, if I have a screen device configured in a particular mode and I reconfigure it to a new, incompatible mode, then I am essentially removing one device and adding another. All reference to the original device is now invalid, and any attempt to reference it is invalid. If, as a programmer using your library, I make an invalid call, I would expect a simple error back. The trickier question now becomes, if I reconfigure it back, am I adding the original device back? I'd say no, it is a new device with the same configuration as one that was previously removed.
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There is no polymorphism. Draw targets are those handles you write to.
draw::point(my_draw_target,spoint16(10,15),color_max::red);
Here,
my_draw_targetis what gets drawn to. above draws a point at (10,16), color of red my_draw_target in this case, is say, screen mode 0 but I now want to switch screen modes// switch the driver to a new screen mode:
auto my_draw_target2 = driver.mode<1>();
// now draw to the new screen
draw::line(my_draw_target2,srect16(0,0,9,14),color_max::antique_white);In the above case, once you have
my_draw_target2,my_draw_targetbecomes persona non grata. How that is handled is the question, meaning what happens if i then try to draw again tomy_draw_target? PS: It may appear that my_draw_target and my_draw_target2 are polymorphic but they are not. They do sort of have a shared interface, but they don't. It's complicated. I bind using templates, not virtual base classesReal programmers use butterflies
The Witch wrote:
I bind using templates, not virtual base classes
That's your problem right there. :laugh:
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The fox knows many things, but the hedgehog knows one big thing. -
No, I've never developed anything in C++. Plenty of other languages, including plain C, but not C++. I have a vague theoretical understanding of what you're doing and would love to have time to explore it more (sadly, I don't) Logically, if I have a screen device configured in a particular mode and I reconfigure it to a new, incompatible mode, then I am essentially removing one device and adding another. All reference to the original device is now invalid, and any attempt to reference it is invalid. If, as a programmer using your library, I make an invalid call, I would expect a simple error back. The trickier question now becomes, if I reconfigure it back, am I adding the original device back? I'd say no, it is a new device with the same configuration as one that was previously removed.
Thank you! That's actually very helpful. I've been considering your approach but my fear was that it would be difficult or counterintuitive. Since you basically articulated to me that you expect precisely one of the avenues I was considering, it seems I have a clear winner in terms of approaches to this.
Real programmers use butterflies
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The Witch wrote:
I bind using templates, not virtual base classes
That's your problem right there. :laugh:
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The fox knows many things, but the hedgehog knows one big thing.It would be impossible to do what I am doing efficiently and by hand in C++ using any other method than what I'm doing. Generic programming has no real substitute in terms of C++ functionality. You basically *can't* replace it with virtual base classes unless you were using it where you didn't need it in the first place. Consider this: I have a pixel. The pixel is user-defined in terms of the number of color channels it has, their names, and what their binary layout, min and max channel values are, etc. This is too involved to compute at run time. It would kill performance Now, for every draw method, it deals in pixels like this, but because a pixel must be typed to its functionality, literally the only way I could make it polymorphic is to use a vtbl every time i needed a pixel. That's just not acceptable in terms of performance. Binding using templates is the solution. That way you can inline, or you can otherwise aggressively optimize away those calls.
Real programmers use butterflies
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It would be impossible to do what I am doing efficiently and by hand in C++ using any other method than what I'm doing. Generic programming has no real substitute in terms of C++ functionality. You basically *can't* replace it with virtual base classes unless you were using it where you didn't need it in the first place. Consider this: I have a pixel. The pixel is user-defined in terms of the number of color channels it has, their names, and what their binary layout, min and max channel values are, etc. This is too involved to compute at run time. It would kill performance Now, for every draw method, it deals in pixels like this, but because a pixel must be typed to its functionality, literally the only way I could make it polymorphic is to use a vtbl every time i needed a pixel. That's just not acceptable in terms of performance. Binding using templates is the solution. That way you can inline, or you can otherwise aggressively optimize away those calls.
Real programmers use butterflies
Wouldn't polymorphic flyweights work? You've piqued my interest. If one of your recent articles discusses this code, please point me to it.
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The fox knows many things, but the hedgehog knows one big thing. -
Wouldn't polymorphic flyweights work? You've piqued my interest. If one of your recent articles discusses this code, please point me to it.
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The fox knows many things, but the hedgehog knows one big thing.I don't have an article that explicitly talks about how the code works, just how to use it. But.. gfx_demo/gfx_pixel.hpp at master · codewitch-honey-crisis/gfx_demo · GitHub[^] Consider the convert<>() routine starting at line 690. It's massive. It's ugly. It would be slow as heck to do at runtime. This will get called width*height times during a call to draw a bitmap when format conversion needs to be done. If any of the routine did not result in aggressive compile time operations, to where this routine translates to a few shifts and multiply/divides at worst - the thing would slow to a crawl if I had any JMPs in there. There are none despite what it looks like, except sometimes for clamping, which often gets compiled to ifless code anyway.
Real programmers use butterflies
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I've been spinning my wheels on a simple design issue I can't decide on for the life of me. I've spent a quarter of the time on this actually writing code - which works, and does everything it needs to - and the rest of that time I've spent on basically one method, and what to return from it. All to switch screen modes, and all because different screen modes *must be* different actual types. So you have to return something from a screen mode change operation that you can draw to. What do I with the old draw target from the previous mode???? This isn't even something I can really ask someone about. I hate problems like this. They leave me feeling paralyzed and frustrated because I can't just code my way out of it. I can't put myself in the shoes of a person using my code in this instance to a degree that satisfies me. So I can't answer the question. I've got $150 worth of hardware that was donated to me on the premise that I would write driver code for it, and I'm stuck on this one stupid issue and at this point it is ruining my day. Yes, I've already taken a break from it. That's why it is taking so long. The question isn't difficult. It's just difficult to decide. *headdesk* Anyway, I'm just venting, and also typing this in hopes that putting it out there might lead to me making some headway, as happens occasionally.
Real programmers use butterflies
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Time to look at some creational design pattern?
"In testa che avete, Signor di Ceprano?" -- Rigoletto
I have no choice but to use the factory pattern for creation.
Real programmers use butterflies
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I've been spinning my wheels on a simple design issue I can't decide on for the life of me. I've spent a quarter of the time on this actually writing code - which works, and does everything it needs to - and the rest of that time I've spent on basically one method, and what to return from it. All to switch screen modes, and all because different screen modes *must be* different actual types. So you have to return something from a screen mode change operation that you can draw to. What do I with the old draw target from the previous mode???? This isn't even something I can really ask someone about. I hate problems like this. They leave me feeling paralyzed and frustrated because I can't just code my way out of it. I can't put myself in the shoes of a person using my code in this instance to a degree that satisfies me. So I can't answer the question. I've got $150 worth of hardware that was donated to me on the premise that I would write driver code for it, and I'm stuck on this one stupid issue and at this point it is ruining my day. Yes, I've already taken a break from it. That's why it is taking so long. The question isn't difficult. It's just difficult to decide. *headdesk* Anyway, I'm just venting, and also typing this in hopes that putting it out there might lead to me making some headway, as happens occasionally.
Real programmers use butterflies
When you're stuck on a super important issue with significant consequences and you just can't decide which of your options is the best one, use The Grand Query Of Decision Making (TGQODM). Its MySQL version looks like this:
SELECT IF(RAND() < 0.5, 'Do option 1', 'Do option 2')
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That is one of the options - to fail on subsequent drawing operations. The other - trickier but doable option is to allow both to continue working, but at the expense of more memory usage (since its holding both frame buffers), and the fact that your whole screen will change when you start to draw to the original target again. I don't want this to be too difficult for people. That's one of the reason I kind of don't like the failing options. The problem with failing is that in this environment I cannot use exceptions. If people don't check return values, the fails are all silent. But maybe in this case that's for the best. After writing this out to you I'm leaning toward that. :thumbsup:
Real programmers use butterflies
Let the developer decide. You are writing an api, right? Choose a default. Allow for the opposite value. Complete the easiest path. By then, reality should be more clear. If not, implement the other path, and repeat the thought process. Finally, how is it handled in other OSes? Older systems? Maybe they were right? Good luck!
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I don't have an article that explicitly talks about how the code works, just how to use it. But.. gfx_demo/gfx_pixel.hpp at master · codewitch-honey-crisis/gfx_demo · GitHub[^] Consider the convert<>() routine starting at line 690. It's massive. It's ugly. It would be slow as heck to do at runtime. This will get called width*height times during a call to draw a bitmap when format conversion needs to be done. If any of the routine did not result in aggressive compile time operations, to where this routine translates to a few shifts and multiply/divides at worst - the thing would slow to a crawl if I had any JMPs in there. There are none despite what it looks like, except sometimes for clamping, which often gets compiled to ifless code anyway.
Real programmers use butterflies
does this help? C++ reading and writing BMP images | Solarian Programmer[^]
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does this help? C++ reading and writing BMP images | Solarian Programmer[^]
Not even a little.
Real programmers use butterflies
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Let the developer decide. You are writing an api, right? Choose a default. Allow for the opposite value. Complete the easiest path. By then, reality should be more clear. If not, implement the other path, and repeat the thought process. Finally, how is it handled in other OSes? Older systems? Maybe they were right? Good luck!
First one is impossible. The code either works one way or it works the other. The second one was basically my approach though both paths were non-trivial. Older OS's and older systems were developed by people that either have never heard of generic programming, or avoided using it, so they've never encountered this issue.
Real programmers use butterflies
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Thank you! That's actually very helpful. I've been considering your approach but my fear was that it would be difficult or counterintuitive. Since you basically articulated to me that you expect precisely one of the avenues I was considering, it seems I have a clear winner in terms of approaches to this.
Real programmers use butterflies
I do not know the details of your code, only what I read in this thread, but I was thinking the same as NeverJustHere with one change. I would probably make the class defining the device/target a singleton so that getting a new target would make the old reference point to the new target and probably no errors would have to be thrown. If a method is added to check the current drawing mode you have all your bases covered. Maybe! :) Hope it helps. Good luck.
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I do not know the details of your code, only what I read in this thread, but I was thinking the same as NeverJustHere with one change. I would probably make the class defining the device/target a singleton so that getting a new target would make the old reference point to the new target and probably no errors would have to be thrown. If a method is added to check the current drawing mode you have all your bases covered. Maybe! :) Hope it helps. Good luck.
Yeah that's not doable because each mode must be a fundamentally different type. You can't represent mode 1 with a class for mode 2. If you could, I'd just have a "set mode" method on the driver class, and then use the driver class as the draw target like i do with my single screen mode drivers.
Real programmers use butterflies
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I've been spinning my wheels on a simple design issue I can't decide on for the life of me. I've spent a quarter of the time on this actually writing code - which works, and does everything it needs to - and the rest of that time I've spent on basically one method, and what to return from it. All to switch screen modes, and all because different screen modes *must be* different actual types. So you have to return something from a screen mode change operation that you can draw to. What do I with the old draw target from the previous mode???? This isn't even something I can really ask someone about. I hate problems like this. They leave me feeling paralyzed and frustrated because I can't just code my way out of it. I can't put myself in the shoes of a person using my code in this instance to a degree that satisfies me. So I can't answer the question. I've got $150 worth of hardware that was donated to me on the premise that I would write driver code for it, and I'm stuck on this one stupid issue and at this point it is ruining my day. Yes, I've already taken a break from it. That's why it is taking so long. The question isn't difficult. It's just difficult to decide. *headdesk* Anyway, I'm just venting, and also typing this in hopes that putting it out there might lead to me making some headway, as happens occasionally.
Real programmers use butterflies
I'm not sure if I even fully understand the problem but it sounds a bit like you could benefit from a design change where you maintain state information for each draw mode. This would allow you to switch between modes without loosing anything since all relevant data would be saved before switching modes.
